A conventionally known liquid crystal display device for cars or the like includes a liquid crystal display having a liquid crystal sealed in between a pair of glass substrates and also having a polarizing plate provided on each of a front side and a rear side of the glass substrates, a circuit substrate having a driving circuit mounted thereon for driving the liquid crystal display, a light source mounted on the circuit substrate and illuminating the liquid crystal display for realizing display, a casing housing the liquid crystal display and the light source, and a see-through plate made of synthetic resin, covering an opening portion on the front of the casing, protecting the liquid crystal display, preventing entry of dust from the outside to the inside of the casing, and allowing excellent visibility of the liquid crystal display. (See, for example, Patent Document 1 and Patent Document 2)
Such a see-through plate made of synthetic resin typically has the advantages of high strength and easy molding in molding even when it has a complicated shape. For example, a polycarbonate resin or an acrylic resin having a transmission property is used. This provides the advantage that the see-through plate covering the front side of the casing can be easily molded from the synthetic resin material even when it has a complicated shape. It is also known that, even when an observer wears polarizing glasses, the use of the polycarbonate resin or the acrylic resin allows favorable visual recognition of practically required display contents on the liquid crystal display through the use of the see-through plate (the substrate made of the synthetic resin) of a polymer material serving as a polarization-property relieving plate which relieves the polarization property on the front side of the liquid crystal display 2.